1. Field of the Invention
The present invention relates to a tensioner which is used for imparting an appropriate tension to a transmission belt or transmission chain in a timing system of an engine or the like.
2. Description of the Related Art
A tensioner 500 has been widely used which includes, as depicted in FIGS. 10 to 12, a tensioner body 510 having a plunger housing hole 511 and a ratchet housing groove 515; a plunger 520 slidably inserted into the plunger housing hole 511; and a ratchet 530 which is disposed in the ratchet housing groove 515 in a state of being capable of swinging on a ratchet pin 540 supported on the tensioner body 510, the ratchet engaging with the plunger 520 and regulating the movement of the plunger 520 toward the housing side (see, for example, Japanese Patent Application Publication Nos. 2006-234088, 2004-44749, and H11-344036).
As depicted in FIGS. 10 to 12, the tensioner body 510 has a hole outer circumferential wall 512 disposed on the outer circumference of the plunger housing hole 511, and a first pin support wall 516 and a second pin support wall 517 which are disposed apart from each other in the pin longitudinal direction of the ratchet pin 540 and support the both end sides of the ratchet pin 540, and the hole outer circumferential wall 512 has a first outer circumferential wall portion 513 and a second outer circumferential wall portion 514 at positions crossing a virtual line L extending in the pin longitudinal direction through the center of the plunger housing hole 511.